Various devices have been proposed or built which are utilized to propel balls, such as tennis balls, automatically. With specific reference to tennis ball pitching machines, the proposed devices have been utilized in practicing for proficiency in the game of tennis. The player positions himself on the court opposite the machine and then returns the balls pitched by the machine as an aid acquiring tennis skills.
However, previously provided tennis ball pitching machines have not provided for the delivery of consistent velocity, proper trajectory, pitched balls, and further, are susceptible to jamming to an extent that their use without an assistant or instructor to continually relieve the jamming of the balls and permit the machine to continue to deliver balls has been impractical.
It has been recognized that to achieve full utilization, a tennis ball pitching machine should provide a means for varying the aim point or delivery point of the pitched ball. For this purpose, prior art machines have provided a means of oscillating the pitching machine about a vertical axis. However, in prior art devices, the means for oscillating the machines has been related in speed to the ball delivery apparatus, such that a tennis ball is propelled in a predictable pattern of delivery points, and therefore the user does not obtain the maximum training effect as would be obtained with a random delivery pattern.
Thus it is desirable to have a tennis ball pitching machine which consistently delivers balls at the same velocity, which has a reduced susceptibility to jamming, and which includes a device for automatically clearing jams and continuing the tennis ball pitching action. Such a device is particularly to be desired where it provides for a delivery of balls in a substantially randomly distributed angular pattern of delivery points.